Bhupaes, your way of thinking is impressive. You didn't find solution, but you said almost everything.
To make physics of modern serve/forehand/1h backhand really clear, let's think in steps.
First, if you look at this forum, at other tennis forums, if you listen to coaches - everybody talks about "loading" energy, more precisely - about adding energies generated in different parts of kinetic chain. This is "your" 5 stage rocket
OK. Do we see this process on the image? Where?